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The Effects of pH on Frog Hearts

PH is the measure of a chemical's acidity and ranges from 0 to 14, with higher numbers denoting alkalinity and lower numbers indicating acidity. Pure water has a neutral pH of 7. Because frogs are dependent on water for reproduction and can respire through their skin, they are particularly susceptible to the effects of environmental pollutants that alter water pH. The cardiovascular system is often the first organ system to be affected by inappropriate pH levels.

Acid Rain
- Chemicals and pollutants on Earth are cycled back into rain through the water cycle. This often causes acid rain, which is rain with an especially low pH. When acid rain comes into contact with a frog's skin, the frog absorbs many of the harmful chemicals in the rain. These chemicals are processed through the frog's entire body, including its heart. Frogs exposed to lots of acid rain have shorter life spans because their hearts grow weaker over time.
Toxic Chemicals
- Not only is water with an unusually high or low pH in itself damaging to frog hearts, but it also increases the damaging effects of other chemicals. Ammonia in particular becomes especially toxic when water is unusually alkaline with a high pH. Some environmental pollutants are absorbed more easily into frog skin when the pH of the water changes. The most common effect of this is that the frog's heart rate may temporarily rise or fall dramatically. These alterations in heart rate are stressful to the frog's entire body and, if they happen frequently, can cause death.
Birth Defects
- Though many frogs live primarily on land, they lay their eggs in water. Thus frog reproduction is often dramatically altered by changes in water pH. Both high and low pH can cause numerous birth defects including extra or missing limbs. Frog hearts have three chambers, which means that their hearts are not as efficient as many land animals' hearts. When frog hearts are exposed to high or low pH as tadpoles or eggs, they may be born with fewer heart chambers, partially developed hearts or highly inefficient hearts.
Disease
- Both captive and wild frogs exposed to inappropriate pH levels are susceptible to a wide variety of systemic diseases. High pH can result in an overgrowth of bacteria and parasites. These may invade the frog's body, ultimately causing heart failure or infection. Water with inappropriate pH also alters oxygenation levels. This causes stress to the frog's heart and respiratory system. This stress can cause death, eliminate reproduction and even result in abnormal behavior.

Animals & Science